>being able to take out enemy satellites (nav, surveillance, missile launch detection, etc)
You can easily do it without having objects in orbit. You can simply launch a ballistic cloud of debris at suborbital speeds and kinetic energy of the targeted satellite will do the rest. Time to hit could be shorter for an orbital system, but not significantly so. This is why I consider the recent news about the Russian orbital satellite killer to be a cheap fearmongering.
You can easily do it without having objects in orbit. You can simply launch a ballistic cloud of debris at suborbital speeds and kinetic energy of the targeted satellite will do the rest. Time to hit could be shorter for an orbital system, but not significantly so. This is why I consider the recent news about the Russian orbital satellite killer to be a cheap fearmongering.